<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<style>
.parent {
    display:grid;
    grid-template-columns:auto 1fr;
    grid-gap:20px
}
</style>
<body>
<div class="parent" style="background-color: lightgrey;">
    <div class="left" style="background-color: lightblue;">
        <p>left</p>
    </div>
    <div class="right" style="background-color: lightgreen;">
        <p>right</p>
        <p>right</p>
    </div>
</div> 


</body>
</html>